Electronic devices such as smart phones, personal digital assistants, location based devices, digital cameras, music players, computers, or transportation, have become an integral part of many daily activities. Key components of these electronic devices are integrated circuit devices. These tiny integrated circuits must perform during daily activities including a wide variety of environmental conditions as well as potentially damaging forces. Many and varied types of packaging, intended for protection, interconnection or mounting, have been developed for integrated circuit devices.
Integrated circuit dies are conventionally enclosed in plastic packages that provide protection from hostile environments and enable electrical interconnection between the integrated circuit die and an underlying substrate such as a printed circuit board (PCB). The elements of such a package include: a lead frame or substrate, an integrated circuit die, bonding material to attach the integrated circuit die to the lead frame or substrate, bond wires or other connectors that electrically connect pads on the integrated circuit die to the lead frame or substrate. The package can also include a plastic or other insulating material that covers the components and forms the exterior of the package.
Wafer manufacturing strives to reduce transistor or capacitor feature size in order to increase circuit density and enhance functionality. Device geometries with sub-micron line widths are so common that individual chips routinely contain millions of electronic devices. Reduced feature size has been quite successful in improving electronic systems, and continuous development is expected in the future. However, significant obstacles to further reduction in feature size are being encountered. These obstacles include defect density control, optical system resolution limits, and availability of processing material and equipment. Attention has therefore increasingly shifted to semiconductor packaging as a means to fulfill the relentless demands for enhanced system performance.
Drawbacks of conventional designs include a relatively large footprint of the package on the mounting surface of motherboard. The footprint reflects dimensions that are typically the maximum of the package, namely, the maximum x-y dimensions of the package. In applications where mounting space is at a premium, such as pagers, portable telephones, and personal computers, among others, a large footprint is undesirable. With the goal of increasing the amount of circuitry in a package, but without increasing the area of the package so that the package does not take up any more space on the circuit board, manufacturers have been stacking two or more die within a single package. Unfortunately, sufficient overlap for electrical interconnect, large footprint top packages, increased device integration, pre-testing, and interconnect lengths have plagued previous package designs.
Thus, a need still remains for a stacked integrated circuit package system to improve area and volume. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to save costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.